Linux Servers to Get Kernel Refresh

by Paul Rubens

OS Roundup: Linus blesses a new kernel. Are you ready to test drive it on your Linux servers?

Linus Torvalds has a message for all the Linux aficionados out there in userland, and the message is this: "Go forth and multiply."

Well not quite. Being the father of the Linux server operating system, the message is actually the slightly more prosaic "Go forth and test." And that-which-must-be-tested is the latest, greatest 2.6.34 Linux kernel, still fresh from the foundry whence it was released last Sunday, less than three months after the previous one.

Now I know what you are probably thinking. A new version of a major Linux server OS distro: interesting. A new version of Windows: intriguing. A new version of OS X: could be fun to play with. But a new Linux kernel? Big deal.

That's certainly what Linus thinks -- he seems to be going out of his way to discourage rubberneckers. "Nothing very interesting here, which is just how I like it. Various random fixes all over, nothing really stands out," is how he put it in the release announcement on the Linux kernel mailing list. "Pretty much all of it is one- or few-liners, I think the biggest patch in the last week was fixing some semantics for the new SR-IOV VF netlink interface. And even that wasn't a _big_ patch by any means."

Of course that doesn't mean that there was nothing of interest at all -- on the contrary, the kernel is packed with cool new stuff. Well, a few cool things, anyway.

Like, for example, the Ceph distributed network filesystem. "Ceph is designed to handle workloads in which tens thousands of clients or more simultaneously access the same file, or write to the same directory-usage scenarios that bring typical enterprise storage systems to their knees," is how it's described on kernelnewbies.

There's also another, experimental filesystem, LogFS, which is specifically designed for flash memory storage devices like solid state drives and USB sticks. LogFS takes into account the way these storage devices erase and rewrite blocks of data, scales efficiently, mounts much faster and has far lower runtime memory requirements than non flash-target file systems.

Then there's an update to Btrfs, the new(ish) copy on write Linux filesystem, which now includes better snapshot control and a new interface for incremental backups. There's also a new userspace utility, btrfs, which replaces the old utilities.

For virtualization buffs there's a new vhost net kernel level backend which, according to kernelnewbies, reduces virtualization overhead, reduces latency by a factor of five, and improves bandwidth to almost native performance. Existing virtio net code is used in guests without modification. There is also a stand-alone version of the VMware Balloon driver, which activates if the host is VMware, that allows the hypervisor to dynamically limit the amount of memory available to the guest.

There's other stuff too, including Kprobes jump optimization, security enhancements, asynchronous suspend/resume, the ability to switch between GPUs, and basic support for Radeon Evergreen GPUs. Improved support for many processor types, notably the ARM processor popular in many mobile devices, as well as driver changes for Nvidia, Intel and Radeon graphics and various networking and storage devices also bear mentioning.

As with all that Linuxy goodness to be getting on with, Linus finished up by declaring the merge window for the open source software officially open. "As usual, I probably won't do any real pulls for a day or two, in the (probably futile) hope that we'll have more people running plain 2.6.34 for a while. But you can certainly start sending me pull requests," he concluded, wearily.

Paul Rubens is a journalist based in Marlow on Thames, England. He has been programming, tinkering and sitting in front of computer screens since his first encounter with a DEC PDP-11 in 1979.

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This article was originally published on Tuesday May 18th 2010
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